The invention relates to a regeneratively operating two-stroke reciprocating internal combustion engine with at least one combustion cylinder (working cylinder), associated with an ignition device and an arrangement for fuel injection and connected via a connecting line wherein a regenerator is provided with a supercharger cylinder, wherein the pistons of the combustion cylinder and of the supercharger cylinder operate with a mutual phase shift by an angle of between 30.degree. and 90.degree., the piston of the combustion cylinder leading the piston of the supercharger cylinder.
In detail, the invention concerns a regeneratively operating reciprocating internal combustion engine with at least two cylinders operatively connected by way of a regenerator, the reciprocating pistons of which move with mutual phase shift, one of the two cylinders, namely the one connected to the cooler end of the regenerator, acting as a charge-changing compression and re-expansion unit whereas the other cylinder, connected to the hot end of the regenerator, serves essentially for fuel preparation and, respectively, operates as a combustion and primary expansion unit.